Opinion: The Burden of Borders

US border policy and fences threaten wildlife across the continent.

By Jesse R. Lasky | October 17, 2011

JaguarWIKIMEDIA COMMONS, JOHN VETTERLI

Jaguars once ranged across the US southwest, but a campaign of extermination up until the 1960s eliminated them from the region. In recent decades a few individuals crossed from Mexico into the United States and took up residence in Arizona and New Mexico, but the jaguar’s recolonization in the States is up against a literal barrier—the extensive man-made fences and walls along the US-Mexico border.

Besides the burden posed to US jaguar recolonization, border barriers pose an extraordinary threat to other species and entire ecosystems. Barriers have recently been constructed across a huge scale, and are not subject to any environmental regulation. As such, dozens of environmental protection laws that we rely upon to protect us and our surrounding ecosystems are legally nullified when the US government chooses to build barriers. The risk is exceptional because the US-Mexico border passes straight through the most biodiverse landscapes of the United States. Large strips of habitat were destroyed and disturbed in the construction of about 700 miles of barriers, along with accompanying roads and nighttime stadium-lighting, all of which involves massive clearing of vegetation and disturbed soil from construction. Furthermore, the fences prevent many larger animals from traveling the large distances necessary to find resources or mates.

Border barriers are a particularly high threat to isolated populations, which face an increased risk of extinction.Populations that get wiped out from a natural disaster are less likely to be re-colonized by others of their species if they cannot migrate easily due to barriers. Additionally, when populations do not exchange migrants, the members of a small isolated population will mate only with each other. This inbreeding results in lower genetic diversity, slowing adaptive evolutionary change and potentially increasing deleterious recessive alleles that depress survival and reproduction. Large mammals like desert bighorn sheep, which are federally protected in the US and Mexico, are particularly under threat. Their populations interconnect across the international border and their migrations will likely be disrupted by fences. Indeed, previous research has found them to be particularly sensitive to interstate highways, for example, that blocked migration and led to a rapid loss of genetic diversity.

US-Mexico border at Tijuana

WIKIMEDIA COMMONS, TOMAS CASTELAZO

Finally, border fences pose a threat to species like jaguars that are in the process of shifting or expanding their ranges in response to environmental change, or other ecological factors. As the Earth warms, many populations have begun moving towards the North and South poles, or towards higher elevations, tracking their preferred climates. Barriers that run latitudinally, such as those along the US-Mexico border, may block species from expanding their range, causing them to be squeezed against the border.

Tim Keitt (University of Texas at Austin), Walter Jetz (Yale University), and I recently published a study that for the first time assessed the risk posed by border barriers to all species of amphibians, reptiles, and non-flying mammals. We identified which border species are most threatened by barriers across their range, such as species with small ranges that could be at risk of extinction from current barriers. In particular, we identified 23 species that already have more than 50 percent of their range blocked by barriers, three of which are listed as globally threatened by the International Union for Conservation of Nature (IUCN). According to our analysis, the wildlife of the California Coast and the Gulf Coast face the greatest threats from current barriers.

Clearly, there is a fundamental conflict between wildlife and the border patrol. On one hand, migration is critical to many wildlife species and secretive animals like to move under the cover of vegetation or night. On the other hand, the border patrol wants to increase visibility and decrease the permeability of the border to stop illegal crossing by humans. For example, the border patrol plans to spray herbicide along the Rio Grande to eradicate Arundo donax, an invasive species of reed that grows tall and dense and provides a good hiding place.

One alternative to physical barriers may be improved remote-sensing technology to allow the border patrol to identify illegal border-crossing without disrupting wildlife dispersal. However, the government recently canceled a “virtual fence” system of remote sensors because it became very expensive and often malfunctioned.

Perhaps a more practical way of reducing the conflict between wildlife and the border patrol is to reduce the quantity of illegal border traffic in other manners, such as improvement in economic conditions in Mexico, increased numbers of worker visas, and policies that reduce the flow of illegal guns and drugs across the border. Some politicians continue to focus on barrier construction, however. The Secretary of Homeland Security still has the authority to fence the entire border at any time, unchecked by any regulatory law, and a bill introduced this year by a Utah Republican Representative would extend the unregulated areas to border patrol activities within 100 miles of the Canadian and Mexican borders. The Obama administration has been pursuing immigration reform that would be linked to heightened border security, possibly by means of physical barriers. And lower level governments may also build barriers; the Arizona State Senate, for example, has recently passed legislation authorizing construction of pedestrian fences.

With such efforts underway, it is imperative that we recognize and study environmental impacts of border barriers. With the proper policy changes and conservation actions, we can limit the ecological damage caused by border policies.

Jesse R. Lasky is a PhD student at the University of Texas at Austin who studies how landscapes affect the ecology and evolution of species and communities.

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Jaguars never "roamed" across the Southwest (certainly not in the last 10,000 years. They have been sporadically present and waxed and waned as the post-Pleistocene populations of their prey species waxed and waned with shifiting climates.

Hello, I don't doubt that their population levels have fluctuated over time. But 19th and early 20th century records show Jaguars in California, Arizona, New Mexico, and Texas, as far north as the Grand Canyon. That is consistent with my statement.

Of course, jaguars are elsewhere, and I even think they show up in Colorado as well--I recall (or think I recall) a latest Pleistocene specimen at the UC museum in Boulder, and are they not recorded in Nevada? My point is that the beast follows the prey and the prey expands and contracts in range as environment come and go. The record through time is not continuous or contiguous in time given the imperfection of the record through time. I could dig out my Art Harris reprints and look for his faunal lists vs environments, of course--perhapsÂ I should. Art has written some grand papers. I sugegst there are very separate issues here: 1) barriers as deliterious to faunal (and I suppose flaoral) dispersion and the result can be comples, e.g., there could be interesting diversification effects of isolating populations; and 2) should a society be forced to leave itself open toÂ social, economic and criminal/terrorist incursion. (1) is an interesting excercise with potentially very interestingÂ Â observations; (2) is a social, criminal, potentially military, political, and economic set of issues that have consequences for an entire nation. One suspects the overiding concerns of (2)--if the impacts are real of course--will have the greater weight.

Jaguars never "roamed" across the Southwest (certainly not in the last 10,000 years. They have been sporadically present and waxed and waned as the post-Pleistocene populations of their prey species waxed and waned with shifiting climates.

Hello, I don't doubt that their population levels have fluctuated over time. But 19th and early 20th century records show Jaguars in California, Arizona, New Mexico, and Texas, as far north as the Grand Canyon. That is consistent with my statement.

Of course, jaguars are elsewhere, and I even think they show up in Colorado as well--I recall (or think I recall) a latest Pleistocene specimen at the UC museum in Boulder, and are they not recorded in Nevada? My point is that the beast follows the prey and the prey expands and contracts in range as environment come and go. The record through time is not continuous or contiguous in time given the imperfection of the record through time. I could dig out my Art Harris reprints and look for his faunal lists vs environments, of course--perhapsÂ I should. Art has written some grand papers. I sugegst there are very separate issues here: 1) barriers as deliterious to faunal (and I suppose flaoral) dispersion and the result can be comples, e.g., there could be interesting diversification effects of isolating populations; and 2) should a society be forced to leave itself open toÂ social, economic and criminal/terrorist incursion. (1) is an interesting excercise with potentially very interestingÂ Â observations; (2) is a social, criminal, potentially military, political, and economic set of issues that have consequences for an entire nation. One suspects the overiding concerns of (2)--if the impacts are real of course--will have the greater weight.

Jaguars never "roamed" across the Southwest (certainly not in the last 10,000 years. They have been sporadically present and waxed and waned as the post-Pleistocene populations of their prey species waxed and waned with shifiting climates.

Hello, I don't doubt that their population levels have fluctuated over time. But 19th and early 20th century records show Jaguars in California, Arizona, New Mexico, and Texas, as far north as the Grand Canyon. That is consistent with my statement.

Of course, jaguars are elsewhere, and I even think they show up in Colorado as well--I recall (or think I recall) a latest Pleistocene specimen at the UC museum in Boulder, and are they not recorded in Nevada? My point is that the beast follows the prey and the prey expands and contracts in range as environment come and go. The record through time is not continuous or contiguous in time given the imperfection of the record through time. I could dig out my Art Harris reprints and look for his faunal lists vs environments, of course--perhapsÂ I should. Art has written some grand papers. I sugegst there are very separate issues here: 1) barriers as deliterious to faunal (and I suppose flaoral) dispersion and the result can be comples, e.g., there could be interesting diversification effects of isolating populations; and 2) should a society be forced to leave itself open toÂ social, economic and criminal/terrorist incursion. (1) is an interesting excercise with potentially very interestingÂ Â observations; (2) is a social, criminal, potentially military, political, and economic set of issues that have consequences for an entire nation. One suspects the overiding concerns of (2)--if the impacts are real of course--will have the greater weight.

Without disagreeing with the supporting points in the above editorial nor with the need to bring construction projects like the fence under environmental review and mitigation, the argument would have been more complete with coverage of environmental damage being done by human migrants crossing the border, by habitat loss due to overpopulation-serving developmentÂ in the areas where the immigrants settle, and due to the extra drain on the already overused natural resources needed by all living things that occurs where the needs of additional migrant people must be met.

One can accept the principle of your argument, however the migrants will be using resources whichever side of the boarder thay live. The reality is to tackle the planetary over-population rather than take a xenophobic view of protecting "your" resources

Without disagreeing with the supporting points in the above editorial nor with the need to bring construction projects like the fence under environmental review and mitigation, the argument would have been more complete with coverage of environmental damage being done by human migrants crossing the border, by habitat loss due to overpopulation-serving developmentÂ in the areas where the immigrants settle, and due to the extra drain on the already overused natural resources needed by all living things that occurs where the needs of additional migrant people must be met.

One can accept the principle of your argument, however the migrants will be using resources whichever side of the boarder thay live. The reality is to tackle the planetary over-population rather than take a xenophobic view of protecting "your" resources

Without disagreeing with the supporting points in the above editorial nor with the need to bring construction projects like the fence under environmental review and mitigation, the argument would have been more complete with coverage of environmental damage being done by human migrants crossing the border, by habitat loss due to overpopulation-serving developmentÂ in the areas where the immigrants settle, and due to the extra drain on the already overused natural resources needed by all living things that occurs where the needs of additional migrant people must be met.

One can accept the principle of your argument, however the migrants will be using resources whichever side of the boarder thay live. The reality is to tackle the planetary over-population rather than take a xenophobic view of protecting "your" resources

Hello, while waivers did not cover all border fences, they covered at least 400 miles of the border (http://www.dhs.gov/xnews/relea..., and the law allows the secretary of Homeland Security to waive laws anywhere on the border.When referring to stadium fencing, do you mean stadium lighting? While stadium lighting does not accompany all fences, it has also been planned for rural areas beyond ports of entry, for instance in central California for 45 miles and east of El Paso for 21 miles.

Hello, while waivers did not cover all border fences, they covered at least 400 miles of the border (http://www.dhs.gov/xnews/relea..., and the law allows the secretary of Homeland Security to waive laws anywhere on the border.When referring to stadium fencing, do you mean stadium lighting? While stadium lighting does not accompany all fences, it has also been planned for rural areas beyond ports of entry, for instance in central California for 45 miles and east of El Paso for 21 miles.

Hello, while waivers did not cover all border fences, they covered at least 400 miles of the border (http://www.dhs.gov/xnews/relea..., and the law allows the secretary of Homeland Security to waive laws anywhere on the border.When referring to stadium fencing, do you mean stadium lighting? While stadium lighting does not accompany all fences, it has also been planned for rural areas beyond ports of entry, for instance in central California for 45 miles and east of El Paso for 21 miles.